1. Field of the Invention
The invention relates to a cosmetic and/or dermatological composition intended for depigmenting the skin, or avoiding the pigmentation of the skin, both of the face and of the body, or even of the scalp. It relates more particularly to a composition comprising at least one active agent which is conveyed via at least two distinct types of lipid vesicles.
The invention also relates to the use of this composition for the cosmetic treatment of the skin, to the use of this composition for the preparation of an ointment intended for the dermatological treatment of the skin and to a cosmetic treatment process for the skin.
2. Discussion of the Background
At various times in their lives, some people develop darker patches on the skin and more especially on the hands, imparting a heterogeneity to the skin. In general, these patches are due to production of melanin on a considerable scale in the epidermis and/or the dermis of the skin.
These patches may be associated with several phenomena and more especially with ageing. In some cases, these patches may become cancerous. Thus, attempts are increasing to diminish, or even to eliminate, these patches.
Numerous depigmenting compositions exist on the market, but the effectiveness of these compositions, is, unfortunately, often insufficient.
Moreover, many examples are known of cosmetic or dermatological compositions intended for treating the skin, which have one or more active agents that are suitable for treating the skin and which are encapsulated in lipid spherules or vesicles (also known as liposomes).
Lipid spherules or vesicles are understood to refer to particles formed of a membrane consisting of one or more concentric lamellae, these lamellae containing one or more bimolecular layers of amphiphilic lipids encapsulating an aqueous phase. The aqueous phase may contain water-soluble active substances and the bimolecular layers of amphiphilic lipids may contain lipophilic active substances.
These spherules generally have a mean diameter of between 10 nm and 5,000 mn.
Among the many documents published regarding this matter there may be mentioned the French Certificate of Addition 2,408,387, which describes a composition based on aqueous dispersions of ionic or nonionic lipid spherules encapsulating at least one active substance. More precisely, this document describes compositions containing at least two dispersions of spherules containing different active agents, for the purpose of obtaining a mixed system, that is to say a system in which a first dispersion of spherules containing a first class of active substance is combined with a second dispersion of spherules containing another class of active substances, which enables the two types of substances to act simultaneously at the time of treatment and possibly to obtain a synergistic effect which would not be produced if these two types of substances were made to act successively and separately.
It is well known that the skin consists of surface layers, the stratum corneum, and of deep layers, the live epidermis and the dermis. Yet the specific delivery of such an active agent into the surface layers and, simultaneously, of the same or another active agent into the deep layers was not known in the prior art.
Thus there remains a need for the simultaneous treatment of both the surface and deep layers of the skin. There also remains a need for a composition of depigmenting skin in need thereof.